fetch_image.cgi: Can't return outside a subroutine ...

I am looking at the code in `https://github.com/CSAILVision/LabelMeAnnotationTool/blob/master/annotationTools/perl/fetch_image.cgi` and keep seeing `return` statement being used outside of a function, like this

```
if(!open(FP,$fname)) {
print "Status: 404\n\n";
return; # <--- this one o_O
}
```

it repeats over an over again, e.g. at lines 24, 49, 74, etc

Perl would throw an error in such cases `Can't return outside a subroutine ...`. Which is expected, because `return` is used to return from a subroutine and there are no subroutines defined in the whole script. Indeed, you will see the error message appear in apache error log if you try with a faked URL (note `collection=empty` that corresponds to no file)

```
tool.html?mode=c&collection=empty
```

What am I missing? Is it just a joke?

打开 annotationTools/perl/fetch_image.cgi，检查第 24、49 和 74 行附近重复出现的 return 语句。使用 tool.html?mode=c&collection=empty 重现请求并检查 Apache 错误日志；解释或解决报告的 outside-a-subroutine 错误即表示完成。

由索引模型根据 Issue 内容生成。